Delta Load Combinations -- Upsert, Replace, Append, Load All

ETL+ delta load options are Load Upsert, Load Replace, and Load Append. Each load option has limitations but can be combined for better coverage. 🚧 Work in progress

In the context of ETL, a delta load (also known as a incremental load) refers to loading/refreshing only the changes or updates that have occurred since the last load.
Delta loading options are designed for situations when a Load All takes too much time or makes heavy demands on the system.
The Load panel on the ETL+ Extract, Transform and Load (ETL) Page offers four load options:
Load All, Load Replace, Load Upsert, and Load Append.

Delta Load Combination Scenarios

	Advantages & Uses
Load Upsert	Fast, can be run many times a day. Updates existing records or inserts new records. See Force Replace when Upsert option below.	Does not delete records from target/data warehouse table
Load Replace	Retains a history of changes. Good for keeping a history of records from the source table. See Force Replace when Upsert, default for others option below.	Can save several versions of source records on the target data warehouse table. Does not use a unique key to identify the target records to replace. (See example 1 below).
Load Append	Good for keeping a history of records from the source table.	May create duplicates on the target data warehouse table depending on the filter values. Good for keeping a history of records from the source table.
Load All	Makes a %100 copy of the source table.	Doesn’t keep any history/older records on the target table.

	How It Works
Load Upsert	Updates existing records on the target table and inserts new records. Example 2: Column with Last Modified Value = `D_LastModifiedDateTime`
Load Replace	Replaces certain records – typically recently updated records. Requires a last-modified column in the source table. Typically a modified date/date-time stamp. Example 3: Load panel configured for Load Replace
Load Append	Appends (adds) all the records on the source table to the existing records on the target table.
Load All	Deletes the target table and loads all records from the source table to the target. Tables configured with other load types can be temporarily converted to Load All with the Force Load All option on the Job page.
Force Replace when Upsert	Tables configured with Load Upsert are temporarily converted to Load Replace by the Force Replace when Upsert, default for others option from the Load type list, Job Properties panel, Job page.
Force Load All	All Tables are temporarily converted to Load All by the Force Load All option from the Load type list, Job Properties panel, Job page.